I think on further reflection you can also state it as "write the story that is within you." Writing what we know isn't just about getting the emotional context right or doing proper research, though both are important of course. It's also writing your story rather than trying to write a story that is meant to be written by someone else. I mean each writer has his/her own individual style. I can't write like H.G. Wells or Arthur Conan Doyle and don't know anyone who can. Others can write stories about Mars or Sherlock Holmes, but only Wells and Doyle can write like Wells and Doyle. Burroughs Mars isn't the same as Wells and neither of them saw Mars like Bradbury did. All three men had valid views of Mars as the backdrop for their stories though. Each writer must write the truth of his/her tale as he/she sees it.

I think on further reflection you can also state it as "write the story that is within you." Writing what we know isn't just about getting the emotional context right or doing proper research, though both are important of course. It's also writing your story rather than trying to write a story that is meant to be written by someone else. I mean each writer has his/her own individual style. I can't write like H.G. Wells or Arthur Conan Doyle and don't know anyone who can. Others can write stories about Mars or Sherlock Holmes, but only Wells and Doyle can write like Wells and Doyle. Burroughs Mars isn't the same as Wells and neither of them saw Mars like Bradbury did. All three men had valid views of Mars as the backdrop for their stories though. Each writer must write the truth of his/her tale as he/she sees it.